The pros and cons of Wegovy for weight loss, assessed honestly

What the trial results show — and how to read them fairly

The STEP 1 trial, published in the New England Journal of Medicine, randomised 1,961 adults with obesity or overweight plus at least one weight-related condition to either semaglutide 2.4 mg or placebo, both alongside lifestyle support. After 68 weeks, the semaglutide group had lost around 15% of their body weight on average; the placebo group lost roughly 2.4%. About one in three participants on semaglutide lost more than 20% of their body weight. Those are meaningful numbers by any clinical standard, and if you have ever wondered whether Wegovy is simply a placebo effect, the scale of that difference between groups gives a clear answer.

The more recent approval of the 7.2 mg dose adds to the picture. The MHRA approved the dedicated single-dose 7.2 mg pen in April 2026, with trials reporting around 20.7% average weight loss over 72 weeks at that dose, territory that narrows the gap with tirzepatide considerably. You can read more about what that approval means for people considering semaglutide on our Wegovy weight loss overview.

The important caveat: trial participants received structured support, and results vary. A meaningful minority experience modest loss; a smaller group experience very substantial loss. Weight is shaped by biology, not willpower, and no medicine produces identical outcomes across every person. Stating this plainly is not pessimism, it is what the data actually show, and a prescriber who tells you otherwise is worth a second opinion.

The side effects that put people off, and which ones tend to resolve

Gastrointestinal symptoms are the most commonly reported effects of Wegovy. Nausea affects a significant proportion of people, particularly in the early weeks and after each dose step up. Vomiting, diarrhoea, constipation and reflux are also reported. The NHS patient information for semaglutide notes that these effects are typically most noticeable when starting or increasing the dose, and often settle within days to a couple of weeks as the body adjusts.

A question our prescribers hear most weeks is whether the nausea ever properly goes away. For most people, it does ease substantially once they reach a stable dose. Eating smaller portions, avoiding high-fat or very rich foods and not eating right before the injection can all help. Fatigue, headache, dizziness and injection-site reactions are also listed as common. These are manageable for the majority of people, though they are the most common reason some stop treatment early.

Rarer but serious effects require urgent attention: severe, persistent abdominal pain that radiates to the back may be a sign of pancreatitis, which the MHRA's Drug Safety Update flagged in January 2026 as an infrequent but potentially serious risk with GLP-1 medicines. Gallbladder problems, allergic reactions and (in people with diabetes) vision changes are also on the list of effects to know about and to report promptly to a healthcare professional. The Yellow Card scheme at yellowcard.mhra.gov.uk is the UK's reporting route for suspected side effects.

Who it is licensed for, and what the eligibility rules actually mean

In the UK, Wegovy is licensed for adults with a BMI of 30 or above, or a BMI of 27 or above alongside at least one weight-related condition such as high blood pressure, high cholesterol, prediabetes or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. These are the private eligibility criteria based on the medicine's licence; NHS access operates under NICE's separate recommendation (TA875), which adds additional requirements including treatment within a specialist weight management service for a maximum of two years.

A BMI figure alone never decides the outcome. A prescriber looks at the whole picture: your medical history, existing conditions, other medicines you take and whether this treatment is appropriate given all of that context. Oral contraceptive users considering Wegovy should also know that no equivalent evidence of reduced absorption has been identified for semaglutide, unlike for tirzepatide, but contraception and medication interactions are still part of a proper clinical assessment. For a fuller look at how private versus NHS access compares on cost, our Wegovy cost guide covers both routes honestly.

If Wegovy does not suit your circumstances, semaglutide is not the only option. Our semaglutide page explains the range of licensed formulations now available, including the oral Wegovy tablet approved by the MHRA in June 2026.

Weighing both sides: what tips the balance

The genuine pros of Wegovy for weight loss are well-evidenced: meaningful average weight reduction, a single weekly injection once you are established on treatment, a long safety and efficacy record built across tens of thousands of participants in the full STEP programme, and now two dose options. For many people who have tried diet and activity changes without lasting success, this is a clinical tool that works by changing the biology of appetite rather than demanding more willpower.

The cons are real too. Side effects are common in the early months. The treatment requires ongoing prescriptions, regular clinical review, and a commitment to the lifestyle changes that go alongside it, Wegovy is not effective in isolation. Weight can return if treatment stops, which means the decision to start is one worth thinking through carefully with a clinician.

Both sides of this balance are worth exploring in more depth. Our overview of what Wegovy does well and our honest look at the downsides go further on each. You can also read a broader treatment comparison on our weight loss treatments page.

If you want a prescriber to assess whether Wegovy is right for your situation, start your free consultation with our team. Every assessment is reviewed the same day by a GPhC-registered Independent Prescriber, not a piece of software.